System for supporting substantially rigid linear structures

ABSTRACT

A suspended supporting system for supporting a substantially rigid linear structure ( 2 ) such as a pipeline, a tramway, a walkway bridge, a transportation gallery, an underwater tunnel, etc. placed above the ground/seabed/riverbed, the system including: apparatus ( 1 ) attached to the linear structure, pulling the linear structure upward, generating upward vertical force of magnitude great enough for carrying downward vertical loads and lateral loads applied to the linear structure; and at least two guy ropes ( 5 ) placed at an angle with each other, upper ends of which are attached to the linear structure and lower ends of which are attached to a footing structure ( 7 ) placed on or anchored in the ground/seabed/riverbed.

The present application is a 35 USC 371 of International Application No.PCT/US00/34019, filed Dec. 14, 1999, and titled SYSTEM FOR SUPPORTINGSUBSTANTIALLY RIGID LINEAR STRUCTURES.

TECHNICAL FIELD

The present invention relates to supporting structures generally and,more particularly, to a novel suspending supporting structure forsupporting substantially rigid linear structures such as pipelines,tramways, walkway bridges, transportation galleries, underwater tunnels,etc placed above a surface.

BACKGROUND ART

While the present invention is described in detail with reference to thesupport of pipelines, it will be understood that it is application aswell to the support of other substantially rigid linear structures suchas pipelines, tramways, walkway bridges, transportation galleries,underwater tunnels, and etc.

Design and construction of supports for linear structures such aspipelines, tramways, walkway bridges, transportation galleries,underwater tunnels, etc. placed in complex terrain, or underwater, or inecologically sensitive areas with long-term recovery of soils destroyedby construction activities, have a long term experience.

Depending on the linear structure, different types of supports arecurrently in use. For example, aerial and underwater pipelines areplaced mostly in trenches dug in the ground and then backfilled,sleepers placed upon the ground, or tower supports. Tramways and walkwaybridges, as well as transportation galleries, are usually supported bytowers or by suspended long-span cable systems.

However all these types of supports have significant drawbacks under theabove conditions.

For example, feasibility and cost effectiveness of placing of thepipelines underground or supporting them by sleepers strongly depends onground conditions: hardness and roughness of the ground. For many casesof irregular terrain, using these supports is completely impossible.Similar restrictions exist for using tower supports. Placed acrossmountainous areas with steep slopes and high peaks, they are ineffectivebecause their heights are significantly higher than the costeffectiveness limits (approx. 100-150 ft). Practically, designers preferto bypass such areas even though it increases the lengths of the linearstructures and accordingly, their costs. Both, sleepers and towers arehighly vulnerable to natural disasters such as snowfalls, landslides,earthquakes, etc., typical occurrences in mountainous areas.

The suspended systems are more suitable for complex terrain but they areused rarely. The main problem of these structures is that the maincarrying cable and the suspended linear structures have low lateralstiffness and are subjected to large displacements and rocking under thelateral loads, mostly wind. To increase the stiffness, traditionalsuspended systems include special structures such as horizontal framesor a number of horizontally interconnected cables, or the like. See U.S.Pat. Nos. 3,604,361 and 3,745,601. As a result, suspended supportingsystems usually fail cost competition with sleepers and tower supports

An effective system of suspended supports for aerial transportationmeans, such as ski lifts, aerial tramways, freight ropeways, etc isdescribed in U.S. Pat. No. 5,655,457. The system described thereinincludes a long-span cable suspended at its ends and placed along thetransportation route A number of spaced apart supports for the aerialmeans are hung from the cable. Each support has a rigid elementsupporting the transportation means carried by the cable and guy ropes,one end of which is attached to the rigid element and another end isanchored in the ground and tensioned. The guy ropes carry lateral loadsapplied to the rigid-elements. No additional structures increasing thelateral stiffness of the system are required. The system is veryeffective for aerial transportation means; however, for carrying linearstructures it has to be essentially modified.

Accordingly, an object of the present invention is to provide asuspended supporting system for linear structures such as pipelines,tramways, walkway bridges, transportation galleries, underwater tunnels,etc, providing lateral stability of the structures by segmenting themand thus, decreasing their free spans in horizontal plane. The mosteffective areas of application of the system are complex terrain andunderwater conditions, as well as ecologically sensitive areas withlong-term recovery of soils destroyed by construction activities

DISCLOSURE OF INVENTION

A suspended supporting system for supporting a substantially rigidlinear structure such as a pipeline, a tramway, a walkway bridge, atransportation gallery, an underwater tunnel, etc. placed aboveground/seabed/riverbed, said system comprising means attached to saidlinear structure, pulling said linear structure upward, generatingupward vertical force of magnitude great enough for carrying downwardvertical loads and lateral loads applied to the said linear structure,and at least two guy ropes placed at angle with each other, upper endsof which are attached to said linear structure and lower ends of whichare attached to a footing structure placed on or anchored in saidground/seabed/riverbed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a side elevational view of the structural elements of asuspended supporting system shown supporting a pipeline.

FIG. 2 is a top view of the system of FIG 1.

FIG. 3 is a cross-sectional view of the pipeline in connection with thecable and the guy ropes

FIG. 4 is a side elevational view of the elements of FIG. 3

FIG. 5 is a diagram of forces applied to system at a point the guy ropesupport is installed, wherein P_(c) is a vertical resultant forceincluding pre-tensioning, force P_(c1) and gravity load P_(c2) appliedto the cable, D_(c1) is a balancing downward loads, P_(g1),-P_(g2) aretensile forces in the guy ropes; and P_(h) is the lateral load appliedto the system (mostly wind), which produces reaction component P_(h1),in one of the guy ropes.

FIG. 6 is a cross-sectional scheme of the guy rope support hung from acarrying cable with a hanger

FIG. 7 is a cross-sectional view of the hanger supporting the pipeline

FIG. 8 is a side elevational view of the hanger.

FIG. 9 is a side elevational view of a suspended supporting systemsupporting an underwater pipeline over the seabed.

BEST MODE FOR CARRYING OUT THE INVENTION

The major goal of this invention is the development of a suspendedsupporting system for substantially rigid linear structures such aspipelines, tramways, walkway bridges, transportation galleries,underwater tunnels, etc. which provides lateral stability of the linearstructures by segmenting them and, thus, decreasing their free spans inthe horizontal plane.

A description of the invention is made with two examples, pipelinesplaced in mountainous terrain and underwater

Referring to the drawings in more detail, in FIGS. 1 and 2, a suspendedsupporting system, according to the present invention, for an aerialpipeline placed across a steep slope is shown.

The main carrying element of the supporting system is a cable 1suspended above the ground. The cable is placed alone the route of theaerial pipeline 2 One cable carries one pipeline placed below andcoincident with cable 1. End 11 of cable 1 is anchored in a supportingstation 13 and end 12 is attached to a tensioning means 15 of asupporting station 14 as is shown or both ends of the cable may beanchored depending on the forces involved. As the tensioning means 15different pulling mechanisms can be used, for example, a balance weight15 as it is schematically shown in FIG. 1 may be used. Tensioning of thecable generates upward forces applied to the pipeline. Due to theseforces, the cable 1 carries the downward loads, mostly weight ofpipeline 2 and the product transported therein. However, these upwardforces, as it is described below, have to exceed the forces necessary tocarry the downward loads because they also have to balance thepre-tensioning, forces in guy ropes 5 that carry the lateral loadsapplied to the linear structure.

Pipeline 2 is hung from the cable 1 by using a number of pipelinesupports 3 and 4 placed along cable 1.

As best seen by reference also to FIG. 3, supports 3 carry the lateralloads applied to pipeline 2 and transfer the downward vertical loadsfrom the pipeline to cable 1. Each of the supports 3 includes a saddle 6attached the pipeline 2 hung from cable 1, and two guy ropes 5 havingupper ends attached to the pipeline and lower ends to footings, as at 7(FIGS. 1,2)

Saddle 6 provides a sliding contact between cable 1 and pipeline 2 incase of elongation, for example temperature elongation, of the cable.The sliding contact is necessary to avoid additional loading caused byelongation of the cable, applied to the guy ropes of the supports 3and/or to the expansion joints of pipeline 2 (expansion joints notshown)

Saddle 6 may be of different design. In the preferred embodiment shownin FIGS. 3 and 4, saddle 6 includes housing 17 attached to a bandage 9embracing pipeline 2. A part of saddle 6 contacting the cable is a trackwheel 18 with a grooved rim 10 placed over the cable 1. When cable 1moves about the pipeline because of elongation of the cable, track wheel18 rolls along the cable and, thus, practically no additional load isgenerated

Connection of guy ropes 5 with pipeline 2 may be of different design. Inthe preferred embodiment, they are attached to extensions 8 of bandage9.

Supports 3 carry the lateral loads, mostly wind loads, applied topipeline 2 and provide lateral stability of the pipeline in the mannerdescribed below. As is shown in FIG. 5, the upward force induced bytensioning of cable 1 is equal to the force P_(c1) balancing downwardloads D_(c1) that is the weight of the structure and live loads appliedto the pipeline, and the force P_(c2) that produces tension forcesP_(g1)=P_(g2) in guy ropes 5A and 5B. As it is also shown, the lateralload P_(h) additionally tensions guy rope 5A by the force P_(h1) Whenthe forces P_(c2), P_(h) and P_(g1)+P_(h1) are balanced, the position ofpipeline 2 at the point where the supports 3 are attached is stable. Incase of opposite direction of the lateral loads, the system workssymmetrically. This means that pipeline 2 is supported in the horizontalplane at these points and works similar to a continuous beam. Thegreater the number of supports 3 that are installed, the less thelateral displacements of pipeline 2. At the same time, due to perfectaerodynamic characteristics of the system, which is practicallytransparent for the wind, the lateral loads applied to the pipeline areminimal.

To reduce displacements of supports 3 caused by temperature elongationof pipeline 2, the supports should be placed in the middle of pipelinesections between two expansion joints. In these case position of thesupports 3 along the pipeline is practically unchangeable at anyelongation of the pipeline and accordingly, no additional loads will beapplied to the guy ropes. In cases where the supports 3 cannot be placedin the middle of the pipeline sections, their upper ends can bedisplaced significantly along pipeline 2 that will overload guy ropes 5In these cases, if it is necessary, a special means providing expansionof guy ropes 5 will have to be connected thereto. As for such a means,different mechanisms can be used, for example, springs that can be alsoused for damping possible vibrations of guy ropes 5. This means allowselongation of the guy rope and provides its tensioning under thelongitudinal displacements.

Lengths of supports 3 determine profile of pipeline 2. After pipeline 2is mounted upon the cable 1, guy ropes 5 are pulled down until thepipeline reaches the designed altitude above the ground at each pointwhere the supports 3 are attached. To adjust the pipeline profile, guyropes 5 are supplied with length adjusting devices, at 19. Lengthadjusting devices 19 may, for example, be turnbuckles that areschematically shown in FIG. 1.

Depending on the profile of cable 1 and pipeline 2, guy rope supports 3can also include a hanger 16 placed between the saddle 6 and the bandage9 as it is shown in FIG. 6. Hanger 16 can be flexible or rigid.Depending on length of hanger 16, additional guy ropes 20 connecting thecable 1 with foundations 7 could be installed to reduce lateraldisplacements of cable 1, the foundations being placed on or formed inground/seabed/river bed

Usually, an allowable free span of the cable in the horizontal plane islonger than those in the vertical plane. In these cases, the systemincludes also supports 4 placed between supports 3 (FIG. 1) The supports4 (FIGS. 7 and 8) transfer weight of pipeline 2 and the producttransported therein to cable 1 as well as smooth the curvature of theprofile of pipeline 2 They consist of a bandage 22 embracing pipeline 2,a hanger 21 connecting pipeline 2 to cable 1 and a hanger supportingmeans 23 providing connection between the hanger and the cable. Themeans 23 can be of different design, for example as is shown in thepreferred embodiment or similar to saddle 6 described above A means 24is included for adjusting the lengths of hangers 21

Erection of the system is performed by the following steps.

1) The carrying cable 1 is installed between its supports 3 One end 11is anchored and the other end 12 is attached to tensioning means 15.

2) Part of the designed tensioning load necessary for stretching cableloaded by empty pipeline 2 is applied to the cable by tensioning means15.

3) Pipeline 2 is welded, isolated, and equipped with supports 3 and 4 onspecial facilities placed next to one, preferably elevated, cablesupports 13 or 14

4) Pipeline 2 is erected by using cable 1 as a ropeway. Pipeline 2 ishung from and is rolled along cable 1. As a rolling means, rollersaddles 18 of the supports 3 (and 4 if necessary) are used. A simplemechanism, such as a winch, is required for transportation of pipeline 2along cable 1 in its designed position

5) When pipeline 2 reaches the designed position, guy ropes 5 ofsupports 3 are lowered to the round and attached to previously builtfootings 7. Then, guy ropes 5 are pulled down until the projectedpipeline profile is formed

6) The tension of cable 1 is increased until required tension force isreached. Then, lengths of the guy ropes 5 are adjusted, if necessary.

The second version of the present invention is a modification of thesystem for its usage as a support for underwater pipelines. A structureof such a system is shown in FIG. 9 Structurally, the system is ratherclose to that shown in FIGS. 1 and 2. The main difference is that upwardforces applied to the pipeline are generated by buoyancy floats 25instead of cable 1. Floats 25 attached to pipeline 2 substitute also forhanger supports 4. Floats 25 can be placed above pipeline 2 as it isshown in FIG. 9, or under the pipeline. In the first case, floats 25 canbe set directly over or distantly from pipeline 2. In the latter case,floats 25 are connected to pipeline 2 by hangers. As a float 25, anempty metal or plastic sphere, balls made of light materials, or acollar spread along pipeline 2 made of a low density material can beused. The upper ends of the guy ropes 5 are attached to pipeline 2,preferably at the same place where the floats are connected, and theirlower ands are attached to footings 7 The main function of guy ropes 5is to carry the lateral loads applied to pipeline 2 caused by underwatercurrents.

Still another version of the system covers cases when buoyancy force ofthe underwater pipeline itself (FIG. 9) is larger than upward forcerequired for the supporting system attached to the pipelines forexample, in case of gas pipelines of large diameter. The only differencebetween this and the second version is that buoyancy floats 25 areeliminated

This invention is not limited to the details shown since variousmodifications and structural changes are possible without departing inany way from the spirit of the present invention. What is desired to beprotected is set forth in particular in the appended claims.

What is claimed is:
 1. A suspended supporting system and a substantiallylinear structure said system supporting said substantially linearstructure, said structure being a pipeline, a tramway, a walkway bridge,a transportation gallery, or underwater tunnel, placed above a surfacesuch as ground or seabed or riverbed, comprising: (a) said substantiallylinear structure is substantially rigid and has a length substantiallygreater than a width thereof; (b) means having a major axis generallyparallel to a major axis of said substantially linear structure moveablyattached to said substantially linear structure pulling saidsubstantially linear structure upward, generating upward vertical forceof magnitude great enough for carrying downward vertical loads andlateral loads applied to said substantially rigid structure; and (c) atleast two guy ropes placed at an angle with each other, upper ends ofwhich are attached to said linear structure and lower ends of which areattached to a footing structure placed on or anchored in said surface.2. The suspended supporting system according to claim 1, including alsoat least one hanger hung from said means having a major axis, placedalong said linear structure between adjacent pairs of said guy ropes orbetween one of said pairs of said guy ropes and a cable support attachedto said linear structure.
 3. The suspended supporting system accordingto claim 2, wherein said hanger includes means for adjusting its length.4. The suspended supporting system according to claim 1, wherein saidmeans pulling said linear structure upward is a suspended carrying cableplaced above said linear structure along its trace, having one endanchored and another end attached to a means for tensioning saidcarrying cable.
 5. The suspended supporting system according to claim 4,wherein said means for tensioning said carrying cable providessubstantially permanent tension stress of said cable of a predeterminedmagnitude.
 6. The suspended supporting system according to claim 5,wherein said predetermined magnitude of tensioning said carrying cableis selectively changeable.
 7. The suspended supporting system accordingto claim 5, wherein said linear structure is hung from said carryingcable by using one or more saddles moveable along said carrying cablesuch that a sliding contact between said linear structure and saidcarrying cable during an elongation of said carrying cable is provided.8. The suspended supporting system according to claim 7, wherein saidlinear structure is hung from said carrying cable by using a hangerattached to said saddle and said linear structure.
 9. The suspendedsupporting system according to claim 8, wherein said hanger includesmeans for adjusting its length.
 10. The suspended supporting systemaccording to claim 1, wherein said means pulling said linear structureupward is a suspended carrying cable placed above said linear structurealong its trace, having both ends anchored.
 11. The suspended supportingsystem according to claim 10, wherein said at least two guy ropesinclude expansion means which allow elongation of said at least two guyropes and provide their tensioning under longitudinal displacements ofsaid linear structure.
 12. The suspended supporting system according toclaim 1, wherein said guy ropes include means for adjusting theirlength.